Performance, Endocrine, Metabolic, and Reproductive Responses of Nellore Heifers Submitted to Different Supplementation Levels Pre- and Post-weaning

The present study was conducted to evaluate the effects of high and low supplementation levels pre- and post-weaning on performance, endocrine, metabolic, and reproductive responses of Nellore heifers. Fifty Nellore heifers with 132 ± 9.9 kg average body weight (BW) and 138 ± 19 days of age were supplemented from 4 to 14 months. The heifers were distributed into five supplementation plans: HH-6 g/kg of BW of supplement pre- and post-weaning, HL-6 g/kg of BW of supplement pre-weaning and 3 g/kg post-weaning, LH-3 g/kg of BW pre-weaning and 6 g/kg of BW post-weaning, LL-3 g/kg of BW pre- and post-weaning, and CC-control, no supplementation. Interactions were not significant (P > 0.10). The level of supplement fed pre-weaning did not affect any of the performance variables evaluated at the end of the experiment (P > 0.10). There was a significant effect of supplementation and level of supplementation fed post-weaning on average daily gain (ADG) and final BW (P < 0.05). Overall ADG was also affected only by supplementation and level of supplement fed post-weaning (P < 0.05) with animals receiving 6 g/kg of BW post-weaning gaining more weight. Follicular diameter was greater in animals that received 6 g/kg of BW post-weaning (P < 0.05). In summary, performance, endocrine, metabolic, and reproductive variables evaluated in the current study were improved by the level of supplement fed post-weaning. Heifers receiving supplementation of 6 g/kg of BW post-weaning had greater responses, independent of the level received during the pre-weaning phase.